Showing papers on "Norbornadiene published in 2007"
TL;DR: The metathesis activity of Grubbs' catalyst 1 was investigated in the presence of N-donor ligands and showed that MIM and DMAP completely or partially transform catalyst 1 into the hexacoordinate species 5a or 5b producing free PCy3, which additionally acts as an inhibitor for the ROMP reaction.
Abstract: The metathesis activity of Grubbs' catalyst 1 was investigated in the presence of N-donor ligands (1-methylimidazole [MIM], 4-(N,N-dimethylamino)pyridine [DMAP], pyridine, and 1-octylimidazole [OIM]). Ring opening metathesis polymerization (ROMP) reactions of cyclooctene (COE), bulk-ROMP reactions of COE and norbornadiene (NBD), and ring closing metathesis (RCM) reactions of diethyl diallylmalonate (DEDAM) were conducted containing various equivalents of N-donor with respect to catalyst. ROMP reactions could be stopped using MIM (1−5 equiv) and DMAP (2−5 equiv), and slowed with pyridine (1−5 equiv) by factors >100, in benzene solution for 24 h. The stopped reactions could be initiated with excess phosphoric acid (H3PO4), and the reactions proceeded faster than with uninhibited Grubbs' catalyst in the first 4 min after reactivation. Thereafter, the reaction proceeded at the same rate as the reaction with the uninhibited catalyst. ROMP reactions in neat COE and NBD could be inhibited for 72 h using 2 equiv ...
114 citations
TL;DR: In this paper, the bridged bis(benzimidazoline-2-germylene)s with different bridging groups have been shown by X-ray diffraction analysis to exhibit different types of weak intermolecular interactions, but no significant Ge·Ge interaction was observed in the solid state.
92 citations
TL;DR: In this article, the long-term stability of polystyrene (s-PS) films with norbornadiene (N) has been investigated by thermogravimetric, infrared linear dichroism and X-ray diffraction experiments.
Abstract: Syndiotactic polystyrene (s-PS) films presenting molecular-complex crystalline phases with norbornadiene (N), possibly suitable for data storage systems with molecular size marks, have been thoroughly investigated. In particular, a procedure suitable for obtaining polymer films containing N molecules only in the crystalline phase and the long-term stability of this s-PS/N molecular-complex crystalline form have been investigated by thermogravimetric, infrared linear dichroism and X-ray diffraction experiments. The possible loss of guest molecules during photoisomerization processes from N to quadricyclane (Q) has also been studied. Moreover, the N and Q patterns obtained by photoisomerization and their long-term stability have been investigated by Fourier transform infrared microscopy.
57 citations
TL;DR: Threefold symmetrical chiral podands may simplify the stereochemistry of key catalytic intermediates for cases in which they only act as bidentate ligands in systems in which chemical exchange between the different kappa2-coordinated forms takes place.
Abstract: Threefold symmetrical chiral podands may simplify the stereochemistry of key catalytic intermediates for cases in which they only act as bidentate ligands. This applies to systems in which chemical exchange between the different κ 2 -coordinated forms takes place and in which the non-coordinated sidearm may play a direct or indirect role at some earlier or later stage in the catalytic cycle. Palladium(II)-catalysed allylic substitutions provide appropriate test reactions along these lines. A series of neutral dichloropalladium(II) complexes, [PdCl 2 (iPr-trisox)] (la), [PdCl 2 (Ph-trisox)] (1b), [PdCl 2 (Bn-trisox)] (1c) and [PdCl 2 (Indtrisox)] (1d) (trisox=1,1,1-tris(oxazolinyl)ethane) were synthesised by reaction of the respective trisox derivative with [PdCl 2 (PhCN) 2 ] and characterised inter alia by 15 N NMR spectroscopy. Direct detection of the heteronuclei without isotope enrichment and with "normal" sample concentrations was achieved with the aid of a cryogenically cooled NMR probe on a 600 MHz NMR spectrometer. Whereas the 15 N nuclei of the coordinated oxazoline rings resonate at δ=160-167 ppm and appear as two singlets due to their diastereotopicity, the signal assigned to the dangling oxazoline "arm" is observed at δ = 238-240 ppm. Variable-temperature NMR studies along with a systematic series of magnetisation transfer experiments established exchange between ligating and non-ligating oxazoline rings. Reaction of [Pd-(allyl)(cod)]BF 4 (cod = cyclooctadiene) with Ph-trisox in CH 2 Cl 2 gave the corresponding allyl complex 2, for which fast exchange between the three oxazoline heterocycles as well as between the exo and endo diastereomers was observed along with a very slow η 3 -η 1 -η 3 process of the allyl fragment (magnetisation transfer). Palladium(0) complexes were prepared by reaction of trisox derivatives or sidearm-functionalised BOX (BOX=bis(oxazolinyl)-dimethylmethane) ligands with [Pd-(nbd)(alkene)] (nbd = norbornadiene, alkene=maleic anhydride or tetracyanoethylene). X-ray diffraction studies of the iPr-trisox and Ph-trisox complexes (3 a and 3b) established Y-shaped trigonal planar coordination geometries with the trisox ligand coordinated in a bidentate fashion, whilst the it-coordinated maleic anhydride ligand adopts one of the two possible diastereotopic orientations. As the catalytic test reaction, the allylic alkylation of 1,3-diphenylprop-2-enyl acetate substrate with dimethyl malonate as nucleophile (in the presence of N,O-bis(tri-methylsilyl)acetamide) was investigated for the trisox derivatives, their BOX analogues, and a series of less symmetric "sidearm" functionalised bisoxazolines. The trisoxazoline-based catalysts generally induce a better enantioselectivity compared to their bisoxazoline analogues and display significant reduction of the induction period as well as rate enhancement.
53 citations
TL;DR: In this paper, the crystal structure of the norbornadiene adduct of one of the isomers, [Rh(PPh3)2(nbd)][1-H-12-(H2CCH)-closo-CB11H10], has been determined.
48 citations
TL;DR: These methods allow us to establish a trend based on the magnitude of iron-rhodium electronic coupling H(ab) ranging from valence trapped to almost delocalised ions.
Abstract: A series of heterobimetallic complexes of general structure [RhL(2){eta(5)-(2-ferrocenyl)indenyl}] (L(2)=cod, nbd, L=CO; cod=cyclooctadiene; nbd=norbornadiene) has been synthesised with the aim of tuning the metal-metal interaction in their mixed-valence ions generated both by chemical and electrochemical oxidation, and the results are compared with those obtained for [RhL(2){eta(5)-(1-ferrocenyl)indenyl}] isomers. Crystallographic studies and DFT calculations provide a detailed description of the structural and electronic features of these complexes evidencing a significant difference in the extent of planarity of the flexible bridging ligand between the 1- and 2-ferrocenyl isomers. Independent experimental probes, in particular the potential splitting in the cyclic voltammograms and the IT bands in the near-IR spectra, are rationalised in the framework of Marcus-Hush theory and at quantum chemistry level by DFT and TD-DFT methods. These methods allow us to establish a trend based on the magnitude of iron-rhodium electronic coupling H(ab) ranging from valence trapped to almost delocalised ions. The quasi planar bridge and the olefin ancillary ligands make [Rh(nbd){eta(5)-(2-ferrocenyl)indenyl}](+) and [Rh(cod){eta(5)-(2-ferrocenyl)indenyl}](+) rare examples of heterobimetallic systems which can be classified as borderline Class II/Class III species.
37 citations
TL;DR: In this paper, a DFT study showed that the different behavior of py and stronger π-acceptor ligands, as CO and PR3 toward 1, has been explained through the DFT analysis.
32 citations
TL;DR: In this article, the Pd center is shown to have a square-planar coordination around the center that is bonded to alkoxy carbonyl and cyano ligands in the trans configuration.
31 citations
TL;DR: The reaction of RuCl(3)(solv.)(n) with tert-butylacetylene in methanol or ethanol leads to the formation of chloro-bridged half-sandwich complexes with sterically demanding cyclopentadienyl ligands, which are of high interest as starting materials for the synthesis of novel Ru catalysts.
30 citations
TL;DR: In this article, the norbornadiene complexes [M(CO)4(pyridyl-CH=N-CHRCO2R′] were obtained by reaction of the Schiff bases from pyridine-2-carboxaldehyde and glycine, L-alanine, l-valine or L-leucine esters.
Abstract: The complexes [M(CO)4(pyridyl-CH=N-CHRCO2R′)] (M = Cr, Mo; R = H, CH3, CH(CH3)2, CH2CH(CH3)2) were obtained by reaction of the Schiff bases from pyridine-2-carboxaldehyde and glycine, L-alanine, L-valine or L-leucine esters with the norbornadiene complexes [M(CO)4(nbd)] and were characterized by IR, 1H and 13C NMR and UV-vis spectra. The deeply colored complexes exhibit solvatochromism.
21 citations
TL;DR: In this paper, the kinetics for the cobalt-catalyzed intermolecular Pauson−Khand reaction (PKR) between (trimethylsilyl)acetylene and norbornadiene (NBD) at a constant CO pressure has been studied.
TL;DR: Several noble metal-olefin complexes were prepared and studied as polymerization catalysts as discussed by the authors, and three different polymer structures were obtained from complexes of the three metals rhodium, iridium, and palladium.
Abstract: Several noble metal-olefin complexes were prepared and studied as polymerization catalysts. Catalytic behavior of complexes toward specific monomers is invariably a property of the metal atom. Polymerization rates may depend upon ligands associated with the metal, but ligands do not alter the course of reaction. Olefin complexes of rho-dium(I) chloride are superior catalysts for the emulsion polymerization of 1,3-butadiene to crystalline trans-1,4-polybutadiene. The rates of polymerization are dependent to some extent upon the olefinic ligands. In all cases rates can be increased by addition of certain hydride donors. Chelating diolefins, such as 1,5-cyclooctadiene and norbornadiene, can serve as stabilizing ligands in catalytically active complexes. When added as free diolefin to polymerizing recipes containing either salts or complexes of rhodium, however, chelating diolefins are effective inhibitors of polymerization. Olefin complexes of iridium(I) chloride do not polymerize butadiene, but are effective catalysts for the ring-opening polymerization of norbornene in bulk, solution, or emulsion. Polymermerization rates are very sensitive to the nature of the ligands within the complex; the more unstable complexes give the faster rates. Specific hydride donors do not usually enhance catalytic activity of iridium complexes, and may lead instead to complete deactivation of the complexes. The selective behavior of complexes of various noble metals toward specific monomers is strikingly illustrated by polymerization of norbornadiene. Three different polymer structures are obtained from complexes of the three metals rhodium, iridium, and palladium. From rhodium polymer consists of nortricyclene units, from a 1,5-addition. Iridium leads to ring-opened oxygenated polymer, whereas palladium catalyzes formation of 1,2-addition polymer.
TL;DR: A series of poly(aryl ether) dendrimers with a norbornadiene (NBD) group attaching to the core (G n -NBD), generations 1-4, were synthesized and characterized, and their photophysical and photochemical properties were examined.
Abstract: A series of poly(aryl ether) dendrimers with a norbornadiene (NBD) group attaching to the core (G n -NBD), generations 1–4, were synthesized and characterized, and their photophysical and photochemical properties were examined. The fluorescence of the dendrimer backbone is quenched by the norbornadiene group as a result of the electron transfer and energy transfer from the dendrimer backbone to the norbornadiene group in G n -NBD. Selective excitation of the dendrimer backbone results in an isomerization of the norbornadiene group to the quadricyclane (QC) group. The intramolecular electron transfer and energy transfer efficiencies are ca. 0.93, 0.73, 0.54, 0.30 in dichloromethane, and ca. 0.90, 0.70, 0.55, 0.34 in tetrahydrofuran for generations 1–4, respectively, with the rate constant ca. 10 10 s −1 . The light-harvesting ability of these dendritic molecules is demonstrated by the enhanced valence isomerization rate of NBD to QC with increasing generation.
TL;DR: Theoretical predictions have been made using density functional theory for the reaction paths of a series of substituted alkynes undergoing a ruthenium-catalyzed cycloaddition with norbornadiene as mentioned in this paper.
TL;DR: In this paper, the reaction of NBD with allyl formate in solutions of Pd0 and PdII complexes occurs selectively, resulting in the product of addition of the allyl fragment and the H atom to an NBD double bond, 5-allylbicyclo[2.1]hept-2-ene, and CO2.
Abstract: Norbornadiene (NBD) reacts with allyl esters All—OC(O)R (R = Me, But, Ph, CCl3, CF3) in acetonitrile solutions of palladium(0) complexes to give a mixture of four isomeric nontraditional allylation products and the corresponding carboxylic acids. Under similar conditions, the reaction of NBD with allyl formate in solutions of Pd0 and PdII complexes occurs selectively, resulting in the product of addition of the allyl fragment and the H atom to an NBD double bond, 5-allylbicyclo[2.2.1]hept-2-ene, and CO2. The hydroallylation of NBD is accompanied by catalytic addition of formic and acetic acids to one double bond of the diene to give bicyclo[2.2.1]hept-2-en-5-ol and nortricyclan-3-ol acetates and formates. Unlike most known palladium-based catalyst systems, these complexes exhibit catalytic activity also in the absence of phosphines.
TL;DR: The tetraphosphine 6A,6B,6D,6E-tetradeoxy (α-TEPHOS) as discussed by the authors is the first optically active tetramerine in which the four phosphine units are tethered to a cavity-shaped scaffold.
Abstract: The tetraphosphine 6A,6B,6D,6E-tetradeoxy-6A,6B,6D,6E-tetra(diphenylphosphinyl)-2A,2B,2C,2D,2E,2F,3A,3B,3C,3D,3E,3F,6C,6F-tetradeca-O-methyl-α-cyclodextrin (α-TEPHOS) has been prepared in high yield by reacting 6A,6B,6D,6E-tetra-O-methylsulfonyl-2A,2B,2C,2D, 2E,2F,3A,3B,3C,3D,3E,3F,6C,6F-tetradeca-O-methyl-α-cyclodextrin with excess PPh2Li. The product was purified in its BH3-protected form. α-TEPHOS is the first optically active tetraphosphine in which the four phosphine units are tethered to a cavity-shaped scaffold. When reacted with [AuCl(tetrahydrothiophene)], α-TEPHOS led to the corresponding tetragold complex [(α-TEPHOS)(AuCl)4] in which the four gold atoms are all located close to the primary face of the cyclodextrin. Reaction with [PdCl(o-C6H4CH2NMe2)]2 gave the C2-symmetrical complex [(α-TEPHOS){PdCl(o-C6H4CH2NMe2)}4]. Treatment of the ligand with two equiv. of [Rh(norbornadiene)(tetrahydrofuran)2]BF4 afforded selectively the bimetallic complex [(α-TEPHOS){Rh(norbornadiene)}2](BF4)2 in which each metal centre is coordinated to two phosphorus atoms belonging to adjacent glucose units.
TL;DR: The versatility of parity reversal, in conjunction with N-substituent steric effects, has been used to produce all three possible stereoisomers of the N,O-sesquinorbornadiene anhydrides in separate, stereoselective cycloadditions as mentioned in this paper.
TL;DR: In this paper, a phenylacetylene bearing an n-butylsulfoxide group was prepared in high yields using the [Rh(norbornadiene)Cl]2-NEt3 catalyst in the presence of various solvents under mild conditions.
TL;DR: In this paper, it was shown that the solar-energy storage system III offers no practicability, and the formation of the alcohols IIIb and IVb has been observed in the presence of water.
Abstract: Norbornadiene derivatives are able to store solar energy under isomerisation to a quadricyclane system. This energy can be liberated by a transition-metal catalysed back reaction. With methanol as a solvent during the isomerisation of dimethylquadri-cyclanedicarboxylate I to the dimethylnorbornadienedicarboxylate II the isomeric nortricyclylmethylethers IIIa and IVa are formed as by-products. In the presence of water the formation of the alcohols IIIb and IVb has been observed. As a result of the side-reactions observed, it is concluded that this solar-energy storage system III offers no practicability.
Patent•
27 Sep 2007
TL;DR: In this article, an organoruthenium compound for use in chemical vapor deposition which does not require the coexistence of oxygen during the thin film formation, and moreover, is liquid at ordinary temperature, thereby having good handleability and recyclability.
Abstract: The present invention is an organoruthenium compound for use in production of a ruthenium or ruthenium compound thin film by chemical vapor deposition, including ruthenium and an arene group and norbornadiene both coordinated to the ruthenium and represented by the following formula. The present invention is an organoruthenium compound for use in chemical vapor deposition which does not require the coexistence of oxygen during the thin film formation, and moreover, is liquid at ordinary temperature, thereby having good handleability and recyclability. wherein the substituents, R 1 to R 6 , of the arene group are each hydrogen or an alkyl group, and the total number of carbons of R 1 to R 6 (R 1 +R 2 +R 3 +R 4 +R 5 +R 6 ) is 6 or less.
TL;DR: A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units was prepared by the Cassar-Heck-Sonogashira cross-coupling reaction and its electroluminescence was tested in a device, and its fluorescence colour could be tuned by light-induced nor bornadiene-quadricyclane isomerization.
Abstract: A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units was prepared by the Cassar-Heck-Sonogashira cross-coupling reaction. Its electroluminescence was tested in a device, and its fluorescence colour could be tuned by light-induced norbornadiene-quadricyclane isomerization.
TL;DR: In this paper, a ring-opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor-acceptor norbornadiene (D-A NBD) dicarboxylic acid was performed.
Abstract: The ring-opening copolymerization of a glycidyl ester derivative having a benzophenone group and the donor–acceptor norbornadiene (D-A NBD) dicarboxylic acid, 5-(4-methoxyphenyl)-1,4,6,7,7-pentamethyl-2,5-norbornadiene-2,3-dicarboxylic acid, monoglycidyl ester derivatives with D-A NBD dicarboxylic anhydride using tetraphenylphosphonium bromide as a catalyst proceeded smoothly to give novel self-photosensitizing NBD polymers in good yields. The molecular weight of these polyesters was about 4,000, and lower than that of analogous NBD polymers having no benzophenone group. All the synthesized NBD polymers isomerized smoothly to the corresponding quadricyclane (QC) polymers upon UV irradiation in tetrahydrofuran (THF) solution and in the film state. The rate of the photoisomerization of the D-A NBD moieties in these polymers was higher than that of the D-A NBD moieties in the polymer having no photosensitizing group. Furthermore, the rate of the photoisomerization of the D-A NBD moieties in these polymers was also higher than that of the NBD polymer with low molecular weight photosensitizer in dilute solution. The photo-irradiated polymers having QC moieties released thermal energies of 146–180 J/g. The D-A NBD moieties contained in these NBD polymers possessed fair to good fatigue resistance. The degradation of the NBD moieties in these polymers was 15–30% after 50 repeated cycles of interconversion. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2978–2988, 2007
TL;DR: In this article, the photochemical reactions of cis-[(η4-NBD)M(CO)4] (NBD is norbornadiene; M=Cr, Mo) with 5-(4-dimethylaminobenzylidene) rhodanine (DABRd) and salicylidsene-3-amino-1,2,4-triazole (SAT) ligands and characterized by elemental analysis, FT-IR and 1H NMR spectroscopy, and mass spectrometry.
Abstract: New complexes cis-[M(CO)4-DABRd] (M = Cr(I), Mo(II) and fac-[M(CO)3-SAT] (M = Cr(III), Mo(IV)) have been synthesized by the photochemical reactions of cis-[(η4-NBD)M(CO)4] (NBD is norbornadiene; M=Cr, Mo) with 5-(4-dimethylaminobenzylidene) rhodanine (DABRd) and salicylidene-3-amino-1,2,4-triazole (SAT) ligands and characterized by elemental analysis, FT-IR and 1H NMR spectroscopy, and mass spectrometry. The spectroscopic studies show that the DABRd ligand acts as a bidentate ligand coordinating via both NH-(S)C=S sulfur donor atoms in I and II and SAT ligand behaves as a tridentate ligand coordinating via its all imine nitrogen-C=N-donor atoms in III and IV to the metal center.
TL;DR: In this article, the cis-to-trans isomerization was also induced when the pristine predominant cis polymer was subjected to mechanochemical grinding (MCG) treatment at 77 K using a mortar filled with liquid nitrogen to decrease the cis content from ca. 68% to ca. 7%.
01 Jan 2007
TL;DR: In this article, the authors summarized the recent progress in the area of exoselective synthesis of polyfluorinated tricyclo[4.1.0 2.5 ]non-7-enes (tricyclononenes) and bicyclo[2.2.1]hept-5-eners (norbornenes).
Abstract: This chapter summarizes the recent progress in the area of exoselective synthesis of polyfluorinated tricyclo[4.2.1.0 2.5 ]non-7-enes (tricyclononenes) and bicyclo[2.2.1]hept-5-enes (norbornenes). The overview of the synthesis polyfluorinated exo- tricyclononenes by reactions of quadricyclane and to lesser extend, norbornadiene is given in the first part of the review. The second part contains information on stereoselective synthesis of polyfluorinated exo- norbornenes and transformations of exo- tricyclononenes.
Patent•
11 Apr 2007
TL;DR: In this article, the process of preparing 2, 5-norbornadiene includes the following steps: adding dicyclopentadiene in the metric amount, acetone as solvent in the amount of 1.5-3.03 wt% of dicycyclopentadien into the tank reactor, and introducing acetylene via stirring to compound the reaction material with dissolved acetylene in 4.0-6.0 molar times.
Abstract: The process of preparing 2, 5-norbornadiene includes the following steps: adding dicyclopentadiene in the metric amount, acetone as solvent in the amount of 1.5-3.0 times weight of dicyclopentadiene and 2, 6-ditertary butyl-4-methyl phenol as polymerization inhibitor in 0.03 wt% of dicyclopentadiene into the tank reactor, and introducing acetylene via stirring to compound the reaction material with dissolved acetylene in 4.0-6.0 molar times of dicyclopentadiene; leading the reaction material into tubular reactor to produce 2, 5-norbornadiene; and decompression rectifying to obtain 2, 5-norbornadiene product. The preparation process inhibits the serial side reactions to raise the reaction yield, ensure stable product quality and lower production cost effectively.
TL;DR: In this paper, the structure of 1b, 2b and 3b were determined by X-ray crystallography and the structures of 1a, 2a, 3a with NaBPh4 affords [Cp*Ru(η6-C6H5C9H8R)] BPh4 (1b, R = H; 2b,R = COOEt) and BPh 4(3b).
Abstract: Formal [2 + 2 + 2] addition reactions of [Cp*Ru(H2O)(NBD)]BF4 (NBD = norbornadiene) with PhCCR (R = H, COOEt) give [Cp*Ru(η6-C6H5C9H8R)] BF4 (1a, R = H; 2a, R = COOEt). Treatment of [Cp*Ru(H2O)(NBD)]BF4 with PhCCCCPh does not give [2 + 2 + 2] addition product, but [Cp*Ru(η6-C6H5CCCCPh)] BF4(3a). Treatment of 1a, 2a, 3a with NaBPh4 affords [Cp*Ru(η6-C6H5C9H8R)] BPh4 (1b, R = H; 2b, R = COOEt) and [Cp*Ru(η6-C6H5CCCCPh)] BPh4(3b). The structures of 1b, 2b and 3b were determined by X-ray crystallography. Copyright © 2007 John Wiley & Sons, Ltd.
TL;DR: In this paper, the authors summarized the recent progress in the area of exoselective synthesis of polyfluorinated tricyclo[4.1.0 2.5 ]non-7-enes (tricyclononenes) and bicyclo[2.2.1]hept-5-eners (norbornenes).
Abstract: This chapter summarizes the recent progress in the area of exoselective synthesis of polyfluorinated tricyclo[4.2.1.0 2.5 ]non-7-enes (tricyclononenes) and bicyclo[2.2.1]hept-5-enes (norbornenes). The overview of the synthesis polyfluorinated exo- tricyclononenes by reactions of quadricyclane and to lesser extend, norbornadiene is given in the first part of the review. The second part contains information on stereoselective synthesis of polyfluorinated exo- norbornenes and transformations of exo- tricyclononenes.
TL;DR: In this paper, a new class of bidentate diphosphite ligands was developed from inexpensive norbornadiene, which exhibited excellent enantioselectivities in the Rh(I)-catalyzed asymmetric hydrogenation of olefin derivatives (up to 99.9% ee).
Abstract: A new class of bidentate diphosphite and diphosphinite ligands has been developed from inexpensive norbornadiene. These ligands exhibited excellent enantioselectivities in the Rh(I)-catalyzed asymmetric hydrogenation of olefin derivatives (up to 99.9% ee).